Fluidic systems



June 24, 1969 J. A. ROCHE FLUIDIC SYSTEMS Filed June 5, 1966 INVENTOR.

United States Patent Oftice 3,451,409 Patented June 24, 1969 U.S. Cl.137-815 5 Claims ABSTRACT OF THE DISCLOSURE A fluidic system isdisclosed wherein the motive fluid supply section includes a containercontaining a solvent for contaminants known to be in the motive gas andmeans for injecting the solvent into suspension in the motive lluid.

The present invention relates to improvements in fluidic devices andmore particularly to supply systems therefor.

In recent years there has been an accelerated effort to vdevelop fiuidicdevices most of which are commonly referred to iluid amplifiers. In suchdevices a fluid power stream is controlled by one or more control jetshaving a substantially lower pressure than the power stream. The powerstream may be deflected towards and away from a receiver port to providepressure changes therein substantially greater than the control jetpressure, hence the term fluid amplifier.

By employing air or other gases, extremely rapid pressure variations canbe obtained, enabling control functions to be perfonmed by inexpensivecomponents with little or no use of electrical or electronic elements.Among other advantages is the capability of operating in ternperatureenvironments which cannot be tolerated by electronic components.

Another potential of iluidic controls is a high level of reliabilityover a long life attributable, to a large measure, to the lack ofmechanical, moving parts. This potential has been diicult to fullyrealize in many instances, particularly where air has been employed asthe motive fluid. Over a period of time it has been found that the fluidamplifier characteristics tend to change so that, for example, a uidiccontrol circuit having a counting function will fail to count all of theinput pulses thereto.

Such malfunctioning is obviously unacceptable for many, if not all,types of controls and accordingly, it is the object of the invention toimprove the reliability of iluidic devices, particularly those in whichair or other gases are employed as the motive Huid.

It has been discovered that air, even after having passed through a highgrade filtration system, contains oil vapors or oil mist droplets whichwill condense or collect on the walls of the llow paths through afluidic device. As this occurs over a period of time, there will be asufiicient accumulation of condensate to change the ilow characteristicsof the air and eventually the tluidic device can Ibe rendered whollyinoperative.

In accordance with this invention it has been discovered that theaddition of small amounts of an atomized, low viscosity, oil solvent tothe air supplied to Huid devices will prevent heavier oils from forminga coating adversely affecting ilow passa-ges in the device. The lowviscosity solvent wets at least all critical surfaces of the `device sothat both the solvent and oil contaminant will be ilushed through thedevice during its operation.

In a broader sense the invention comprises providing means for addingsmall amounts of solvent to the motive uid supply of fluidic devices andthereby preventing condensate buildup on the llow walls which wouldalfect operation of the device.

The above and other related objects and features of the invention willbe apparent from a reading of the following description of thedisclosure found in the accompanying drawing and the novelty thereofpointed out in the appended claims.

The single figure in the drawing diagrammatically illustrates thepresent invention supplying motive uid to an illustrative iluidicdevice.

A conduit 10 extends from an appropriate source of pressurized air to afilter 11 which removes solid contaminants and some vapor contaminantfrom the air. The air then passes through conduit 12 to an atomizer 14.

The atomizer 14 comprises a solvent container 16, a venturi throat 18'and a passageway 2l) from the bottom of the container to the throat 18.As air passes from the inlet 12 to discharge passage 22, a controlledamount of solvent is atomized in the -air stream. The amount of solventmay be varied by adjusting a screw 24 which controls the inlet area ofthe: passageway 20. A conduit 25 connects the upper end of the container16 to the conduit 12 in order to insure a substantially uniform additionof solvent as its level in container 16 varies.

A groove 28 and depending trap 30 are provided downstream of the throat18 to collect solvent that is not atomized. The trap may be periodicallydrained by opening valve 32.

The solvent bearing air is then directed to a uidic device 34 by aconduit 36 which preferably is connected tto the upper side of thedischarge passage 22. The iluidic device 34 is essentially the same asthat disclosed in U.S. Patent No. 3,220,428, issued in the name ofRobert B. Wilkerson and assigned to the same assigne as the presentapplication. Reference is made thereto for further details beyond thosegiven in the following brief description.

The fluidic device 34 controls iiow of lluid through a conduit 36 inresponse to displacement of flappers 38 and 40. When either or both ofthe ilappers 38, `40 are displaced towards tubes 42, 44 respectively,they will cause shifting of a valve piston 46 to either permit or shutolf the flow of Huid through the conduit 36.

The solvent bearing air enters a passageway 48 of the lluidic device 34and is discharged from a nozzle 50 as a power stream or jet. The device34 .may be referred to yas a bistable uid amplifier by reason of thefact that the power stream will attach itself to either of the wallsurfaces 52 or 54 to maintain a constant elevated pressure level ineither of vented `chamber 56 or 58. As illustrated, the power stream isattached to the surface 52 and the pressure within the chamber 56 istransmitted by passageway 60 to the lefthand end of the valve 46,maintaining it in an open position so that there is flow of duid throughthe conduit 36.

The solvent bearing air from conduit 26 also passes through lateralpassageways 62, 64 to chambers 66, 68 respectively. Needle valves 74, 76may be employed to provide equal pressures in the chambers 66, 68 whichare vented through the tubes 42, 44. lFluid from the chambers 66, 68 isdirected from control nozzles 74, 76 laterally against the power streamdischarged from the nozzle 50. The power stream, once attached to eitherof surfaces 52, '54 will remain so attached so long as the control jetsare of equal pressure or the jet from nozzle 76 is greater. Under theillustrated conditions, if the iiapper 38 is moved to restrict ventingof air through the tube 42, there will be an increased pressure in thechamber 66 and the control jet discharged from nozzle 74. This willdisplace the power stream toward the right causing it to become attachedto the surface 54 and increase the pressure in the chamber S8. This inturn will cause an increase in pressure on the right-hand end of thepiston 46 which is connected to chamber 58 by passageway 59. The piston46 will then be displaced to a position in which the ow of iluid throughconduit 36 is shut ol. The power stream will remain attached to the wallsurface 54 when the llapper 38 is moved outwardly to allow the tube 42to vent air from the chamber 66 in the normal fashion and will remain soattached until ow of air from the tube 4-4 is restricted by the apper40.

For economical operation it is desirable that the source of pressurizedair to which the conduit 10 is connected is a factory air supply. It isknown that such a supply is contaminated to a relatively high level withoil vapors and mists as well as vapors and mists of other relativelyheavy petroleum products. For practical and economical reasons, theilter 11 is not intended, nor does it function, to remove such vaporsand mists or droplets from the air as it passes to conduit 12.

The solvent in container 16 is selected as a petroleum solvent having arelatively low viscosity, gasoline, petroleum ether, and kerosene beingillustrative. For the most part, such solvents remain in suspension inthe motive air as it passes through the lluidic device 34. This solventbearing air wets the passageways of the device 34 to prevent the vaporsand mist droplets of the heavier oils from condensing or depositing onany of the functional wall surfaces of the device. The contaminantvapors `and mist droplets thus pass through the fluidic device and haveno effect on its operation, even over long periods of time.

It has been found that very small amounts of solvent are required forthe purpose of the present invention. For example, a kerosene solventadded in the range of 1% to 1/1000 of 1% on a weight basis to air hasbeen found successful in preventing contamination of fluidic devicesusing factory air supply as the motive fluid source.

Where it is known that other non-lterable (in a practical sense)contaminants are in the supply air for a iluidic device, then anappropriate solvent may be selected in accordance with the principlesdiscussed in connection with a heavy oil contaminant. As a furtherexample, salt spray might become ingested in the supply air source. Inthis case distilled water could be selected as the solvent. Similarly, aliquid device employing hard water as its motive uid could employ diluteacids as the solvent to prevent calcium deposits. It will further berecognized that temperature can have an etect on what would constitute aproper solvent. In colder temperatures gasoline would be a moreeffective oil solvent, whereas at higher temperatures kerosene would bepreferred.

It will thus be apparent that variations from the preferred embodimentdeescribed will occur to those skilled 4 in the art and that the scopeof the invention is thus to be derived from the following claims.

Having thus described the invention, what is claimed as novel anddesired to be secured by Letters Patent of the United States is:

1. A lluidic system comprising,

a iluidic device, having a plurality of relatively small passageways,

conduit means connected to a source of pressurized fluid and supplyingmotive fluid to said device, said pressurized fluid having a knowncontaminant therein, which has a propensity for collecting on the wallsof the relatively small passageways,

means for removing the contaminant from the walls of said relativelysmall passageways of said lluidic device comprising, a solvent for saidknown contaminant, and

means for introducing a relatively small amount of said solvent intosaid conduit means whereby said contaminant will be maintained insuspension in said motive fluid and pass through the iluidic device inoperation thereof.

2. A fluidic system as in claim 1 wherein,

the conduit means are connected to a source of pressurized gas and theintroducing means take the form of atomizing means which introducesolvent as a function of the rate of gas flow through the conduit means.

3. A fluidic system as in claim 1 wherein,

. said pressurized iluid comprises air contaminated with heavy oilvapors, and

said solvent comprises a petroleum product having a relatively highvapor pressure.

4. A fluidic system as in claim 3 wherein,

the introducing means take the form of atomizing means.

5. A fluidic system as in claim |4 wherein,

the atomizing means are adjustable to add between 1/1000 of 1% and 1% ofsolvent to air on a weight basis.

References Cited UNITED STATES PATENTS 1,748,488 2/1930 McCabe137-101.11 2,714,963 8/1955 Lester et al 137-101.11 3,022,743 2/1962Engholdt 137-815 XR 3,122,165 2/1964 Horton 137-815 2,220,428 11/ 1965Wilkerson 137-815 3,243,014 3/1966 Bjorklund 137-101.11 XR 3,267,964 8/1966 Steinmetz 137-93 XR SAMUEL SCOTT, Primary Examiner.

